New opportunities to understand heterogeneous catalysis processes on nanoscale bimetallic particles through synchrotron radiation and theoretical studies

New advances in theoretical background and recent experimental results concerning nanoscale bimetallic clusters are presented. From theoretical point of view, we will show how both the relaxation of the intermetallic distances and the chemical local ordering can be predicted from the electronic structure. Here, we compare these predictions at thermodynamical equilibrium to a review of recent results obtained using XAS for bimetallic systems Pt–M where M is a 4d transition metal. Even though the distribution of the two species inside the cluster can be affected by preparation parameters, such as, the nature of the precursor, it appears that these theoretical calculations are a valuable starting point for the study of such entities.     

Effect of defects of the domain structure on the optical properties of ferroelectric crystals

The effect of irregularities of a periodic domain structure on the efficiency of the second harmonic generation has been numerically investigated in the case where the structure is formed by the high-voltage method. The irregularities associated with the uncontrollable motion of domain walls from under electrodes, as well as with the presence of internal defects in the crystal, have been analyzed.     

Mono-, Bi- and Multifunctional Single-Sites: Exploring the Interface Between Heterogeneous and Homogeneous Catalysis

This mini-review contrasts the characteristics of traditional heterogeneous (solid) catalysts with those of homogeneous ones: the nature of the active sites in each case is very different, a fact well illustrated in ammonia synthesis. It is recalled that certain chemical transformations can be effected only with heterogeneous catalysts. It is also demonstrated that the scope for introducing multifunctional sites is greater with open-structured inorganic heterogeneous catalysts than with homogeneous ones: for example, Ti^IV ions distributed in a spatially isolated and accessible manner at the large areas of a nanoporous support smoothly convert cyclohexene to adipic acid (with H₂O₂) in a cascade of six consecutive reactions. A sharp distinction is drawn between nanocluster and nanoparticle “metal” catalysts, both electronic and geometric arguments being utilized to explain this difference. In the extreme case, a few (or single) metal atoms (supported on oxides) have been shown (see refs. Fu et al. Science 301:935, 2003 and Rim et al J Phys Chem C 113:10198, 2009) to be more important determinants of catalytic activity than nanoparticle metals such as Au and Pd. Recent advances in high-resolution electron microscopy is a key technique in this facet of catalysis. The merits of immobilizing single-site homogeneous catalysts and of creating atomically well-defined single-site heterogeneous ones on high-area solids are illustrated both from a practical viewpoint and also as a strategy for the design of new catalysts.     

Effect of mechanical activation on thermal explosion in Ni-Al mixtures

The effect of mechanical activation (MA) on thermal explosion in equimolar Ni-Al mixtures was studied by time-resolved XRD. MA was also found to increase the burning velocity and decrease the ignition temperature. Thermal explosion in non-activated Ni-Al mixtures was found to proceed via formation of liquid (melted) intermediate products, while that in the activated mixtures gave no liquid intermediates.     

Ozonization of Mongolian and Russian lignite and the derived humic acids

The ozonization products of regular and oxidized lignite, semicoke, and humic acids consist of a mixture of aliphatic monocarboxylic and dicarboxylic acids and aromatic polycarboxylic acids of the benzene, naphthalene, and phenanthrene series.     

Stabilization of coke properties

Rational organization of coke stabilization is considered, for various examples. On the basis of the existing relations between the coke and blast-furnace shops, a method is proposed for determining the number of turns in the Micum drum required to obtain the maximum and most economical stabilization.     

More efficient operation of the dust-free coke-discharge modules at OAO Zaporozhkoks coke batteries 5 and 6

Two types of dust-free coke-discharge modules are generally employed. The modules employed at OAO Zaporozhkoks are described and analyzed. Methods are proposed for determining their operational efficiency and testing their performance in plant conditions. Recommendations are made for improving the operational efficiency of dust-free coke-discharge modules mounted on door-opening machines.     

Copolymers containing electronically isolated indolyl fragments as materials for optoelectronics

Monomer and its copolymers containing electronically isolated indolyl fragments were synthesized by multi-step synthetic route. The materials were examined by various techniques including thermogravimetry, differential scanning calorimetry, UV and fluorescence spectrometry as well as electron photoemission technique. The copolymers exhibit initial mass loss temperatures in the range of 259–321 °C and form amorphous films with glass transition temperatures of 102–122 °C. Thin layers of the materials demonstrate ionization potentials of about 5.7 eV. The copolymers were tested as host materials in electro-phosphorescent devices.     

The physical–chemical study of detonation nanodiamond application in adsorption and chromatography

In the present work, the study on detonation nanodiamond (DND) powders modifications in gaseous media was carried out. The surface properties of DND were studied by TGA, IR-spectroscopy, pH-potentiometry and chromatography methods. It was determined that modifying the DND surface reduces specific retention volumes and retention times of adsorbates. At the same time, specific and dispersion interactions have decreased. Such phenomena are significant for gas chromatographic separation of complex mixtures. The study of DND in contact with water and water solutions showed that chemical modification of DND produces on its surface oxygen-containing groups with acidic character. The latter stipulates its ion-exchange properties and applicability to liquid chromatography. In summary, the performed research provides significant perspective toward new-generation adsorbent creation with controlled surface identification for gaseous and liquid chromatography purposes.